The present invention concerns catalyst compositions for polymerizing olefins which comprises a combination of at least one supported titanium-containing catalyst and at least one other separately supported organometallic catalyst and the polymerization of olefins therewith.
Kaminsky et al have shown in Makromol. Chem., Rapid Commun., Vol. 4, pp. 417-421 that a homogeneous halide-free catalyst system consisting of bis(cyclopentadienyl) titanium compounds and bis(cyclopentadienyl) zirconium compounds with polymethylaluminoxane derivatives as cocatalysts are highly active for polymerizing ethylene at temperatures below 100.degree. C. At temperatures above 100.degree. C., low molecular weight polymers are produced.
It has now been discovered that these complexes plus similar complexes of Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Nb, Mo, Ce, Pr, Nd, Th, Pa and U can be employed in conjunction with titanium based catalysts to yield polymers having broader molecular weight distributions and are multimodal, i.e. the polymers have at least two different molecular weight distributions appearing as two well resolved peaks in the gel permeation chromatograms.